Personally, I wouldn't touch a Dell with a barge pole. Even if you gave me one for free.
I'd have to disagree. For years I have always built my own computers from scratch (or seriously upgraded) but obviously with laptops this is not possible. I have found Dell's to be solidly built and always excellent. I preferred the older generation of dell laptops to the current ones as they were not over-engineered.
Obviously you are looking at desktop computers and not laptops, Dell UK customer service has always been very good to me (but used to cost extra, 90 day warranty was standard from Dell until a few years ago). We use Dell computers at work, although they are covered in my companies bloatware, they run very well. As long as you know what your looking for, there are often decent Dell offers in the newspaper, you can get a decent spec'd computer at a good price. One earlier poster suggested getting a friend in the know to customize one to meet your requirements, this is also a good idea, but I doubt you will get the same level of customer care. The ebay seller has a higher likelihood of going out of business and if anything were to break, you would have to deal with the component manufacturer directly which will be difficult, costly and prone to error.